The instant messaging service will be discontinued everywhere except for mainland China, but users can switch to Skype

Microsoft has announced it will retire its instant messaging service on March 15 and asked users to switch to Skype.

Messenger will be shut down globally except for mainland China, Microsoft's Messenger team wrote in an email sent to users on Wednesday. Messenger users will still be able to contact their friends using their Messenger account if they download Skype, Microsoft said.

"You'll be able to instant message and video chat with them just like before, and also discover new ways of staying in touch with Skype on your mobile and tablet," Microsoft said.

On March 15, Messenger will continue to work as usual but people that are logged in on their desktops will see a banner notification asking them to switch to Skype. When a user clicks on the banner, Skype will be downloaded and installed and Messenger will automatically be uninstalled, Microsoft said. After the 15th, desktop Messenger users will be unable to log in to the program and only be able to switch to Skype.

The banner notification will be shown in the newer versions of Messenger; older versions will not receive a notification and users of older versions will be required to download Skype manually, Microsoft said.

Skype lets users communicate via instant message, and offers video calls and IP telephony as well as group video calls for Skype Premium subscribers. Skype is available for devices including PCs, Macs, iPhones, iPads, Android devices, the Kindle Fire, and will soon be available for Windows Phone 8, Microsoft said.

Android , iPhone, and Windows Phone 8 mobile Skype applications can be signed in to with a Microsoft Messenger account over the next few weeks, Microsoft said. iPhone users are already able to do so.

Microsoft bought Skype for $8.5 billion in 2010 and has said from the start that it had big plans for Skype beyond maintaining it as a separate service. The company announced in November that Messenger would be closed down in favor of Skype. In the same month, Microsoft launched a Skype-centered hub for small businesses.

The company is also busy working to integrate Skype into its enterprise productivity and collaboration products including SharePoint and Office.